We are carrying on research on two areas of cellular immunology: 1) The reaction of B lymphocytes to antigen, and 2) The role of macrophages in immune induction. We are studying mechanisms of membrane redistribution, trying to establish the relationships, if any, between capping of surface Ig molecules in B cells and the contractile apparatus of the cell. Also, the effects of ligand-receptor complexes in B cell function insofar as induction and tolerance is being investigated. Finally, our work on macrophages is concerned with the characterization of biologically active molecules secreted upon interaction of macrophages with particles or with lymphocytes.